Tunneling Magneto Resistor Nano-columns*

Nanowires inside carbon nanotubes (CNTs), nano-columns, and thin films of ferromagnet /insulator/ ferromagnet (FM/I/FM) tunneling magnetoresistance (TMR) were synthesized using magnetron DC/RF sputtering [1]. Nanowires were synthesized inside CNTs using glancing angle deposition. The magnetic properties of nanowires, nano-columns and planar nano-metric thin films of FM/I/FM showed similarities including two-fold magnetic symmetry. Nanowires of Fe/MgO/Fe showed enhanced magnetic properties in particular a high increase in coercive field, 754% higher compared to planar thin films of Fe/MgO/Fe [1]. This could be due to shape anisotropy in nanowires, which play an important role in coherence. TMR of nano-columns and nano-metric thin films of FM/topological/FM are other examples studied. TMR is a macroscopic phenomenon that can only be explained by quantum mechanics, where electrical resistance varies when an external magnetic field is applied parallel to the tri-layer system.

[1] D. Seifu, Nanowires of Fe/MgO/Fe Encapsulated in Carbon Nanotubes, Nanowires-Synthesis, Properties and Applications, IntechOpen 2018.